[texhax] TFM format question

[Reinhard Kotucha]

On 2011-04-20 at 13:21:32 -0600, Doug McKenna wrote:

 > Reinhard Kotucha wrote -
 > 
 > >These values are calculated automatically when the tfm file is created
 > >but it seems that they are not used by TeX because characters < 33 are
 > >accessible.
 > 
 > Do you mean "inaccessible"?

No, if you run  

  tex fontchart

you see the glyphs in the DVI file.  You can also try

  \font\manfont=manfont
  \manfont \char0 \char1 ....

 > >Maybe you have to look into the sources.  Do you get the same results
 > >if you convert the TFM file to PL and then back to TFM?  I get:
 > >
 > > $ cmp manfnt-1.tfm manfnt.tfm 
 > > manfnt-1.tfm manfnt.tfm differ: byte 93, line 1
 > >
 > >This is the only byte which differs, it's 0x00 in the original file
 > >and 0x80 in the converted one, but I don't know its meaning.
 > 
 > If I counted correctly, byte 93 is the "seven_bit_safe" flag.  It
 > makes sense that it's being set, as there are no character codes in
 > the file >= 128.
 > 
 > I still don't understand what the consequences are of declaring glyph 
 > dimensions in a TFM file for a character code outside the internally 
 > declared [begin_char:end_char] range.  Maybe none (other than wasted 
 > space).

It would be helpful to know how this range is determined.

Regards,
  Reinhard

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Reinhard Kotucha                                      Phone: +49-511-3373112
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